VGA specification

Hi all, Does any of you knows where can I obtain the VGA specification (I believes it is IBM's) ? Thanks in advance, Mordehay.

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me_2003
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I would be interested in this too. Could you forward me this information too?

Thanks, Derek

Reply to
Derek Simmons

Are you sure you actually want the VGA specification (pretty plain and limited) or do you want the specs for what it evolved into?

Also, what are you looking for - timing, electrical, programming?

Reply to
cs_posting

For quite a while now, most video standards have been handled by VESA. To support plain-Jane VGA, they have a set of "fallback" timings to run a monitor at 640x480 or

720x480 at:

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If you want to support other resolutions, they have a spreadsheet at:

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that allows you to enter resolution, refresh rate, etc., and it calculates timing parameters for you (and verifies whether what you're asking for will be supported by a typical display).

VESA has quite a few more standards as well, but without more information about what you're doing, it's hard to guess which would apply. You can look through the others starting from:

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to find what applies to what you're doing.

--
    Later,
    Jerry.
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Reply to
Jerry Coffin

Yes, knowing the application is the key.

Depending on what you need to do, you can treat a VGA monitor is either an analog, or a nearly digital device.

For just getting something on monitor, several of the FPGA intro boards (spartan 3 kit, etc) have VGA connectors and sample projects that demonstrate a state machine producing the timings. These typicall drive the sync signals directly with LVCMOS outputs and the three color lines either through a single resistor (270 ohms on the s3kit) or a

2-bit resistor ladder dac per channel, to give a few more digital colors. A real DAC gives even more.

Trying to use an FPGA to make a "VGA card" for a pc would be a more complicated project, in which case a lot of the register-level detail of the basic VGA card would need to be known.

Reply to
cs_posting

hi.. check this good page.. this a video timing calculator...

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I used it to make a driver for vga and ntsc interfaces...

good luke.. luis mexico

Reply to
jluisky

I'm looking for a functional spec rather than a timing spec. I remember reading an article that described some of the functionality of CGA, EGA and VGA. When most people in this group inquire about a VGA adapter what they are actually asking for is a frame buffer that generates video timing signals for a multisync monitor for an IBM PC. I would like references for the original IBM 256 Kb VGA adapter or something newer (supporting the new video modes).

I'd really like to hear from somebody that was connected with or has documentation from TSENG. I seem to remember back in the day their VGA adapter's, for the cost, were a step a head of the competition.

I'm going to spend the rest of the night reading the documents from the VESA website.

Derek

Reply to
Derek Simmons

_Programmer's Guide to the EGA, VGA, and Super VGA Cards_ by Richard Ferraro has pretty decent descriptions of most of the graphics cards that were current when it was published, including a couple from Tseng Labs. I haven't checked, but I'd guess this has been out of print for a while though, so you'll probably have to find a used copy to get it. The ISBN is (was) 0-201-62490-7.

Of course, quite a bit of it won't be applicable to what you're apparently doing, but it has register-level descriptions of the interface the cards presented to the rest of the machine, and for the VGA and similar cards, that tells you quite a bit about its internal structure as well.

I would note, however, that much of the design of the VGA (for one example) was a long ways from ideal in a modern system. Much of the architecture of the VGA centered its connection to an 8-bit bus. If you're creating a graphics controller in an FPGA, there's no reason to restrict your bus to it to only 8 bits wide unless you're planning on emulating an entire PC design so you can run PC software on your system. Otherwise, you might as well use a wide bus to connect the graphics to the rest of the system, which will simplify the overall design a LOT. Believe me, the VGA design really put a lot of effort into getting decent performance in spite of a narrow bus, so if you can start from a clean slate, you can do a LOT better.

--
    Later,
    Jerry.
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Reply to
Jerry Coffin

Jerry Coffin writes: |> > Does any of you knows where can I obtain the VGA specification (I |> > believes it is IBM's) ? |> |> For quite a while now, most video standards have been |> handled by VESA. To support plain-Jane VGA, they have a |> set of "fallback" timings to run a monitor at 640x480 or |> 720x480 at: |> |>

formatting link
|> |> If you want to support other resolutions, they have a |> spreadsheet at: |> |>
formatting link
|> |> that allows you to enter resolution, refresh rate, etc., |> and it calculates timing parameters for you (and verifies |> whether what you're asking for will be supported by a |> typical display).

The official VESA list of video timings is a document called

Monitor Timing Specifications -- VESA and Industry Standards and Guidelines for Computer Display Monitor Timing, Version 1.0, Revision 0.8, September 17, 1998, dmtv1r08.pdf. (That's the version I have a copy of, there may well be newer versions.)

Sadly, that seems not to be freely available on the VESA web site. You may have to order and pay for it.

The DMT standard is in the same format at the SMT document above, but contains a pretty complete list of all the commonly used VGA timings. The SMT is basically a 2-page extract of the full DMT list.

What the DMT document does not contain is the electrical and mechanical specifications for the VGA connector. There seems to be no formal standard; in fact there seems to be not even strong agreement on whether full white is represented by 0.7 V ("Euro", VESA),

0.714 V (RS-343) or 1.0 V (RS-170). VESA has AFAIK never fully formally standardized IBM's 15-pin VGA connector. General wisdom appears that the RGB lines are 75 ohm impedance, while the sync lines are TTL (on > 2.4 V, off < 0.5 V at driver, >2.0 V and < 0.8 V at receiver) with 2 kiloohm termination.

Markus

--
Markus Kuhn, Computer Laboratory, University of Cambridge
http://www.cl.cam.ac.uk/~mgk25/ || CB3 0FD, Great Britain
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Markus Kuhn

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